Usage Summary of item views and item widgets controls in QT

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0、 Preface

In the use of QT When making data table presentation , Most of them use tables , List or type tree structure ,QT The commonly used controls in show item view（List 、Tree、Table、Colum、undo view） also item wigets（List 、Tree、Table、Colum、undo view） How to choose , It mainly looks at the difference and connection between the two ：

0.1 contact

In terms of inheritance , item wigets Are inherited from the corresponding item wiew, Generally speaking, in terms of function items widget Easier to use .

0.2 difference

1、 item wigets It's easier to use , and item wiew The usage of is relatively complicated .
2、item views It can store a lot of data （ For example, hundreds of thousands or even millions ）, Users will not get stuck when browsing the data in the table ; Even though item wigets It can also be used to store large amounts of data , However, users may get stuck when using , And the more data displayed , The more obvious the similar phenomenon is .
3、 They are different when loading data sources ：item views Pass count attempt / Modeling separates data from presentation , Therefore, data binding is required when using , Colleagues modify data directly in model modify ,item wigets The data source can be considered to be loaded normally through the function , It is more convenient to use .

The following is a specific example （ item wigets choose QTableＷidget , item wiew choose QTableView ）

4、 Other view The main function ：

QListView： Used to display single column list data , It is applicable to the operation of one-dimensional data
QTreeView： Used to display tree structure data , It is applicable to the operation of tree structure data
QTableView： Used to display tabular data , It is applicable to the operation of two-dimensional tabular data
QColumnView： Use multiple QListView Displays the tree hierarchy , One layer of the tree structure uses a QListView Show
QHeaderView： A view component that provides row headers or list headers , Such as QTableView Row header and list header
UI There are two types on the control panel , Of course, you can also directly define .

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1、item views（ With QTableView As an example ）

view The simple code is as follows ：（ Omit the inclusion of some header files ）

Widget::Widget(QWidget *parent): QTableView(parent)
{
    
   QStandardItemModel* model = new QStandardItemModel(this);
   model->setItem(0, 0, new QStandardItem("test1")); 
   model->setItem(0, 1, new QStandardItem("test2"));
   model->setItem(0, 2, new QStandardItem("test3"));
   this->setModel(model);
}

It's simple , Direct one view Put one in model, All data changes are in model function , The interface is displayed in view On , Although there is no agent here , But the default proxy is already used ：QStyledItemDelegate;

2、item widgets（ With QTableWidget As an example ）

QTableWidget The simple code is as follows ：（ Omit the inclusion of some header files ）

    // Set the header 
    TableWidget.setHorizontalHeaderLabels(QStringList() << "1" << "2" << "3");
    // Set the contents of each row in the table 
    TableWidget.setItem(0,0,new QTableWidgetItem("test1"));
    TableWidget.setItem(0,1,new QTableWidgetItem("test1"));

Friendly to novices , Simple setup .

３、 Customize

I understand View - Model - The relationship between agents ： Trying is actually part of the presentation , such as ui Show part , A model is actually a collection of data , Agents actually define a way of trying to present data , All three have default types .
Just say View/model situation , When you need to re edit model perhaps delegeta Well
1、 Using standard model, Such as QStandardiTemModel, When providing data , It may not reach the optimization we want , Such as real-time data , Then we can inherit again QStandardiTemModel perhaps QAbstractItemModel Re actualize data function
2、 Redefining delegate When , Mainly for customized things , If there is a drop-down box in the table , Check the box for such content , By default, the requirements cannot be met , You need to customize delegate.

The main suggestions here are inherited from QStyledItemDelegate（ I am too lazy to type ）

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summary

1、QTreeView Customize model： Large data volume display – Performance and memory optimization
2、QT Official documents